Biochips such as a protein chip, peptide chip and DNA chip are widely used for diagnosis and research of various diseases. The biochips which have been widely used are usually obtained by immobilizing biologically relevant substances such as a protein, peptide and DNA on a glass substrate such as a slide glass.
However, the conventional biochips using the glass substrate were likely to cause non-specific adsorption and had a problem in accuracy of measurement. Also, since the glass substrate induces autofluorescence, measurements employing fluorescent labels which have been often used recently, had a problem in accuracy.
In order to solve these problems, a substrate for biochips, in which a carbon-containing layer having an active group(s) is formed on a metal substrate, and a biologically relevant substance(s) is/are bound to the active group(s), is provided (Patent Document 1). This substrate for biochips has excellent properties that autofluorescence is not induced, a biologically relevant substance(s) can be immobilized easily, processing of the substrate is easy, and high flatness and surface precision can be attained. However, to increase the adhesion between the metal substrate and the carbon-containing layer in this substrate for biochips, it is necessary to form a nickel-phosphorus (NiP) layer therebetween by an electroless plating, which results in high cost.
Further, a substrate for biochips, in which an amino group-containing polymer is covalently bound on the substrate at least the surface of which is composed of carbon, is also provided (Patent Document 2). The biologically relevant substance is covalently bound to the amino group. This substrate for biochips also has excellent properties as that described in Patent Document 1. However, in cases where the whole substrate is formed as carbon substrate such as amorphous carbon, calcination for about one month is necessary for carbonization of a resin, which requires production cost and time. In cases where a carbon-containing layer is formed on the metal substrate, as in the substrate for biochips described in Patent Document 1, it is necessary to form a nickel-phosphorus (NiP) layer between the metal substrate and the carbon-containing layer by an electroless plating for increasing the adhesion therebetween, thereby resulting in high cost.
On the other hand, a carbon-coated aluminum material, in which a carbon-containing layer is formed on the surface of an aluminum material, and further an interposing layer composed of aluminium carbide is formed therebetween, is known (Patent Document 3). This carbon-coated aluminum material is suitably used as an electrode structure such as an electrochemical capacitor and electrolytic condenser, and use as a substrate for biochips is not described or suggested in Patent Document 3.